Ji Zheng

The Influence of Rare Earth Oxide on the Structure and Properties of AgSnO2 Electrical Contact Materials

In order to develop new electrical contact materials with better properties, small amounts of rare earth (RE) oxides were selected as additions into AgSnO2-based composites. The effects of different RE oxide additions with different content in the matrix on the microstructure of AgSnO2, were investigated. In general, the resulting RE oxide-doped materials are found to have better performances than their original ones. Results indicate that the newly developed AgSnO2/La2O3 materials in this paper are leading candidates for environmentally friendly electrical devices and RE oxides would play an important role in improving performance of AgSnO2.

Study on New Types of Environmental Protection AgSnO2 Electrical Contact Materials

AgSnO2 contact materials have begun to replace toxic AgCdO materials in switching devices such as contactors and circuit breakers since 1970s [1,, which is partly due to the fact that AgSnO2 materials have shown higher service lives, better welding resistance and less arc erosion in contactors of larger size [. Furthermore, the growing awareness of environmental problems makes it desirable to replace AgCdO contact materials [. However, these materials suffer from an inadequate welding behavior compared with AgCdO [. It was observed that AgSnO2 made by traditional metallurgical process exhibited high overtemperatures attributed to high contact resistance caused by surface layers of accumulated SnO2, which was due to the poor wettability of SnO2 grains in the silver melt in combination with their high thermal stability [6,7]. Another important point was the large size and high hardness of SnO2 particle prepared by traditional process, which reduced the workability of AgSnO2 contact materials [8]. In this work, the authors prepared Ti4+-doped SnO2 using sol-gel technique and investigated the microstructure, size, distribution and crystallization of Ti4+-doped tin oxide grains as well as the doping effects on the electrical conductivity of these materials.

Investigation on Nano-Sized ZnO Powder Doped with Al3+ Prepared by Sol-Gel Method

Al3+-doped ZnO nano-powder was prepared by sol-gel process, using tin tetrachloride and titanium tetrachloride as starting materials. The crystallinity and purity of the powder were analyzed by X-ray diffraction spectrometer (XRD). And the size and distribution of Al3+-doped ZnO grains were studied using transmission electron microscope (TEM) and scanning electron microscope (SEM). The results showed that the Al3+ was successfully doped into the crystal lattice of tin oxide and that the electric conductivity of Al3+-doped ZnO sample was improved significantly.